The present study was designed to evaluate the role of lymphoreticular cells; macrophages, T and B lymphocytes and granulocytes within tumors in controlling tumor growth and metastasis. 4 separate studies were performed. First, the tumor associated cellular response to two chemically induced tumors which expresses different degrees of immunogenicity was analyzed from tumors' appearance to animal death. Briefly, a primary immune response with high T cell numbers and high levels of macrophage activation was expressed early in the tumors, but the secondary response was suppressed. Nevertheless, chemotactic forces remained in effect because high macrophage numbers were attracted into the tumor even as the animals were dying. Second, a similar study was performed with a series of primary chemically induced tumors. Results were similar to those described above for the passaged tumors. Third, an immunohistologic study was performed on the primary tumors with anti-T cell and anti-macrophage sera. Again the results were confirmatory. Fourth, an analysis of over 80 primary human tumors has been performed. The results demonstrated that many of those tumors were infiltrated by large numbers of macrophages. BIBLIOGRAPHIC REFERENCES: Wood, G.W. and Gollahon, K.A. Comparative Analysis of the Tumor Associated Cellular Immune Response to Two Syngeneic Passaged Chemically Induced Murine Fibrosarcomas. Fed. Proc. 36: 1222 (1977). Gollahon, K.A. and Wood, G.W. Characterization of the Tumor Associated Host Cellular Response to Primary 3-Methylcholanthrene Induced Murine Fibrosarcomas. Proc. Amer. Asso. Canc. Res. 18: (1977).